Photoperiodism is associated with the formation of

Options

A. auxin
B. florigen
C. vemalin
D. gibberellin

Answer

**Step-by-Step Solution:**

1. **Understanding Photoperiodism**:
- Photoperiodism is the physiological reaction of organisms to the length of day or night. It is particularly important in plants for regulating their development and flowering based on the duration of light exposure.

2. **Identifying the Options**:
- The options provided are:
A. Auxin
B. Florigen
C. Vemelin
D. Gibberellin

3. **Analyzing Each Hormone**:
- **Auxin**: This hormone is primarily involved in processes such as apical dominance, root formation, and cell elongation, but it is not directly related to photoperiodism.
- **Florigen**: This is a flowering hormone that is indeed related to the flowering process in response to photoperiod, but it is not the primary hormone associated with photoperiodism itself.
- **Vemelin**: This is considered a growth substance and is associated with vernalization, which is the process of inducing flowering in response to prolonged cold, not directly related to photoperiodism.
- **Gibberellin**: This hormone is known to promote growth and is involved in various developmental processes, including flowering in response to photoperiod.

4. **Conclusion**:
- Based on the analysis, gibberellin is the hormone that is most closely associated with photoperiodism, as it plays a significant role in regulating flowering and other developmental processes in response to day length.

5. **Final Answer**:
- Therefore, the correct answer is **D. Gibberellin**.

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